With a rapid development of the frequency conversion control technology and a promotion of a concept of raising efficiency and saving energy, a large progress has been achieved on controlling a permanent magnet synchronous motor. However, some deficiencies still occur in controlling a power factor of the permanent magnet synchronous motor.
For example, when a control method of Id=0 or Maximum Torque Per Ampere (MTPA) is used to control the motor, the power factor is not controlled, and if the load of the motor is heavy or the flux weakening is deep, then the power factor is getting worse, such that an actual requirement can not be satisfied. In addition, when a motor angle is estimated without a location sensor, since the location estimation is completed based on a situation in which operation parameters of the motor are relatively accurate, the control of Id=0 will become a flux increasing control or a flux weakening control if the operation parameters of the motor are not accurate, such that an actual control effect may not be achieved.